<?php
$search = array ( "/(\w{6}\s\(w{2})\s(\w+)/e",
                  "/(\d{4})-(\d{2})-(\d{2})\s(\d{2}:\d{2}:\d{2})/");

$replace = array ('"$1 ".strtoupper("$2")',
                  "$3/$2/$1 $4");

$string = "Posted by John | 2007-02-15 02:43:41";     

echo preg_replace($search, $replace, $string);?>